Philips M3001A M3000-60003 M3000-60002 M3000-60001 NIBP Module Dtailed Description

The M3001A module is the PHILIPS MP series parameter modularized MMS module. The NBP part has the highest failure rate in M3001A, which includes two major parts: the mechanical part; The second part is electronic circuit. NBP measures the patient's systolic blood pressure, diastolic blood pressure, and mean blood pressure.

The mechanical part of NBP module is divided into: air pump, pressure sensor, solenoid valve, all of which are integrated in M3001A module. The PN number is m3000-60002 NBP module. The electronic circuit includes: amplifying and filtering circuit, pressure sensor pressure compensation circuit, drive circuit, A/D conversion circuit, microprocessor circuit, NBP program control circuit

NBP module is mainly composed of all the mechanical components of NBP (1 air pump, 2 pressure sensors, 2 solenoid valves) and part of the electronic circuit (part of the filter amplifier circuit and pressure compensation circuit). It is an important part of NIBP noninvasive blood pressure measurement.

1. Mechanical components of NBP module
The mechanical component of the NBP module consists of an air pump, two solenoid valves, and two pressure sensors. The work of air pump and solenoid valve is completely controlled by drive circuit and NBP program control circuit. And their normal operating voltage is as follows:
The air pump in NIBP's mechanical assembly is driven by 12VDC, and the two solenoid valves are also driven by 12VDC, while one pressure sensor is a four-pin pressure sensor powered by 5V dc, and the other is a pressure sensor powered by + / -5v.

1. 2. Electronic circuits in NBP module
The electronic circuit in NBP module is mainly composed of 2 OP291 differential amplifiers and related capacitors and resistors. The circuit diagram of the filtering and amplifying circuit is shown in figure 3. It collects electrical signals from the signal end of the pressure sensor, amplifies them through the differential amplifying circuit composed of two amplifiers OP291, and adds a bias compensation at the reverse phase end of OP291, which can better suppress zero drift and reduce the error of the non-invasive blood pressure value.

Electronic circuit for noninvasive blood pressure measurement
The program control circuit mainly controls the working state of the drive circuit, and then controls the opening and closing of the air pump and the stop air pump and the solenoid valve. The amplifying and filtering circuit filters and amplifies the electrical signals output by the pressure sensor, and then converts the electrical signals into digital signals through A/D conversion circuit, and displays all the measured values through the monitor screen through the microprocessor circuit.
3. NIBP blood pressure measurement trouble solving example
Fault 1: in adult blood pressure mode, when the NIBP pump button is pressed for blood pressure measurement, the noise produced by the air pump cannot be heard, and the air pump does not pump. After some time, the screen says "NBP device failure."
According to the working principle, it can be inferred that the fault causes the fault phenomenon are as follows: (1) air pump fault. (2) pressure sensor failure. (3) drive circuit.
Firstly, the NBP module is removed from the M3001A module, and a set of 12V dc voltage is used to power both ends of the air pump. The air pump can pump normally, so the fault of the air pump is eliminated.
Then, the voltage of the module interface without NBP module is detected as 12V, + / -5v and other groups of voltages. At the same time, the driver chip (F1N05) on the drive circuit of NIBP blood pressure measurement was detected without short circuit, and the chip was normal. F1N05 is an N channel enhanced MOS tube, which can be detected with the diode of multimeter. Also eliminated the fault of the air pump.
Finally, when the NBP module is disassembled, it can be seen that the pins of the two pressure sensors have turned black, and the resistance value between each pin is infinite. After replacing the pressure sensor, the NBP function of M3001A module returns to normal.
Fault 2: air leak. Various forms of fault performance, the most common fault phenomenon is: (1) press the key, the air pump has been pumping, after a period of time, in the screen display three "?" . (2) after pressing the air button, in a certain stage of intermittent air, sometimes can measure the blood pressure of the three parameters, sometimes can not measure the blood pressure of the three parameters.
The fault belongs to the mechanical part, which is caused by the irregular operation of the solenoid valve in NBP module. Because in the air pump pump, the solenoid valve is not completely closed, so that the air pressure value does not reach the predetermined pressure value, finally let the program control circuit repeatedly to the air pump drive circuit work signal.
Solution: (1) disassemble the NBP module, replace the solenoid valve. Troubleshooting. NIBP measurements returned to normal. (2) replace the whole NBP module, NIBP measurement returned to normal.
Fault 3: it can pump air. The real-time pressure value of the cuff displayed on the screen obviously makes people feel that there is a big error. At the same time, the blood pressure value cannot be measured normally. The voltage deviation of 5V provided to NBP module was detected to be very large, only about 3V. After the NBP module was disassembled, the power supply direction of 5V voltage was tracked with a multimeter, and it was found to be the power supply pin of one of the amplifiers, OP291 chip. According to the amplification circuit diagram of the pressure sensor in FIG. 3, the NIBP measurement returned to normal after replacing the OP291 core.